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-rw-r--r--Documentation/trace/events.txt207
-rw-r--r--Documentation/trace/postprocess/trace-vmscan-postprocess.pl18
-rw-r--r--Documentation/trace/uprobetracer.txt36
3 files changed, 247 insertions, 14 deletions
diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 37732a220d33..c94435df2037 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -287,3 +287,210 @@ their old filters):
prev_pid == 0
# cat sched_wakeup/filter
common_pid == 0
+
+6. Event triggers
+=================
+
+Trace events can be made to conditionally invoke trigger 'commands'
+which can take various forms and are described in detail below;
+examples would be enabling or disabling other trace events or invoking
+a stack trace whenever the trace event is hit. Whenever a trace event
+with attached triggers is invoked, the set of trigger commands
+associated with that event is invoked. Any given trigger can
+additionally have an event filter of the same form as described in
+section 5 (Event filtering) associated with it - the command will only
+be invoked if the event being invoked passes the associated filter.
+If no filter is associated with the trigger, it always passes.
+
+Triggers are added to and removed from a particular event by writing
+trigger expressions to the 'trigger' file for the given event.
+
+A given event can have any number of triggers associated with it,
+subject to any restrictions that individual commands may have in that
+regard.
+
+Event triggers are implemented on top of "soft" mode, which means that
+whenever a trace event has one or more triggers associated with it,
+the event is activated even if it isn't actually enabled, but is
+disabled in a "soft" mode. That is, the tracepoint will be called,
+but just will not be traced, unless of course it's actually enabled.
+This scheme allows triggers to be invoked even for events that aren't
+enabled, and also allows the current event filter implementation to be
+used for conditionally invoking triggers.
+
+The syntax for event triggers is roughly based on the syntax for
+set_ftrace_filter 'ftrace filter commands' (see the 'Filter commands'
+section of Documentation/trace/ftrace.txt), but there are major
+differences and the implementation isn't currently tied to it in any
+way, so beware about making generalizations between the two.
+
+6.1 Expression syntax
+---------------------
+
+Triggers are added by echoing the command to the 'trigger' file:
+
+ # echo 'command[:count] [if filter]' > trigger
+
+Triggers are removed by echoing the same command but starting with '!'
+to the 'trigger' file:
+
+ # echo '!command[:count] [if filter]' > trigger
+
+The [if filter] part isn't used in matching commands when removing, so
+leaving that off in a '!' command will accomplish the same thing as
+having it in.
+
+The filter syntax is the same as that described in the 'Event
+filtering' section above.
+
+For ease of use, writing to the trigger file using '>' currently just
+adds or removes a single trigger and there's no explicit '>>' support
+('>' actually behaves like '>>') or truncation support to remove all
+triggers (you have to use '!' for each one added.)
+
+6.2 Supported trigger commands
+------------------------------
+
+The following commands are supported:
+
+- enable_event/disable_event
+
+ These commands can enable or disable another trace event whenever
+ the triggering event is hit. When these commands are registered,
+ the other trace event is activated, but disabled in a "soft" mode.
+ That is, the tracepoint will be called, but just will not be traced.
+ The event tracepoint stays in this mode as long as there's a trigger
+ in effect that can trigger it.
+
+ For example, the following trigger causes kmalloc events to be
+ traced when a read system call is entered, and the :1 at the end
+ specifies that this enablement happens only once:
+
+ # echo 'enable_event:kmem:kmalloc:1' > \
+ /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger
+
+ The following trigger causes kmalloc events to stop being traced
+ when a read system call exits. This disablement happens on every
+ read system call exit:
+
+ # echo 'disable_event:kmem:kmalloc' > \
+ /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger
+
+ The format is:
+
+ enable_event:<system>:<event>[:count]
+ disable_event:<system>:<event>[:count]
+
+ To remove the above commands:
+
+ # echo '!enable_event:kmem:kmalloc:1' > \
+ /sys/kernel/debug/tracing/events/syscalls/sys_enter_read/trigger
+
+ # echo '!disable_event:kmem:kmalloc' > \
+ /sys/kernel/debug/tracing/events/syscalls/sys_exit_read/trigger
+
+ Note that there can be any number of enable/disable_event triggers
+ per triggering event, but there can only be one trigger per
+ triggered event. e.g. sys_enter_read can have triggers enabling both
+ kmem:kmalloc and sched:sched_switch, but can't have two kmem:kmalloc
+ versions such as kmem:kmalloc and kmem:kmalloc:1 or 'kmem:kmalloc if
+ bytes_req == 256' and 'kmem:kmalloc if bytes_alloc == 256' (they
+ could be combined into a single filter on kmem:kmalloc though).
+
+- stacktrace
+
+ This command dumps a stacktrace in the trace buffer whenever the
+ triggering event occurs.
+
+ For example, the following trigger dumps a stacktrace every time the
+ kmalloc tracepoint is hit:
+
+ # echo 'stacktrace' > \
+ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
+
+ The following trigger dumps a stacktrace the first 5 times a kmalloc
+ request happens with a size >= 64K
+
+ # echo 'stacktrace:5 if bytes_req >= 65536' > \
+ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
+
+ The format is:
+
+ stacktrace[:count]
+
+ To remove the above commands:
+
+ # echo '!stacktrace' > \
+ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
+
+ # echo '!stacktrace:5 if bytes_req >= 65536' > \
+ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
+
+ The latter can also be removed more simply by the following (without
+ the filter):
+
+ # echo '!stacktrace:5' > \
+ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
+
+ Note that there can be only one stacktrace trigger per triggering
+ event.
+
+- snapshot
+
+ This command causes a snapshot to be triggered whenever the
+ triggering event occurs.
+
+ The following command creates a snapshot every time a block request
+ queue is unplugged with a depth > 1. If you were tracing a set of
+ events or functions at the time, the snapshot trace buffer would
+ capture those events when the trigger event occured:
+
+ # echo 'snapshot if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ To only snapshot once:
+
+ # echo 'snapshot:1 if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ To remove the above commands:
+
+ # echo '!snapshot if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ # echo '!snapshot:1 if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ Note that there can be only one snapshot trigger per triggering
+ event.
+
+- traceon/traceoff
+
+ These commands turn tracing on and off when the specified events are
+ hit. The parameter determines how many times the tracing system is
+ turned on and off. If unspecified, there is no limit.
+
+ The following command turns tracing off the first time a block
+ request queue is unplugged with a depth > 1. If you were tracing a
+ set of events or functions at the time, you could then examine the
+ trace buffer to see the sequence of events that led up to the
+ trigger event:
+
+ # echo 'traceoff:1 if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ To always disable tracing when nr_rq > 1 :
+
+ # echo 'traceoff if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ To remove the above commands:
+
+ # echo '!traceoff:1 if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ # echo '!traceoff if nr_rq > 1' > \
+ /sys/kernel/debug/tracing/events/block/block_unplug/trigger
+
+ Note that there can be only one traceon or traceoff trigger per
+ triggering event.
diff --git a/Documentation/trace/postprocess/trace-vmscan-postprocess.pl b/Documentation/trace/postprocess/trace-vmscan-postprocess.pl
index 4a37c4759cd2..00e425faa2fd 100644
--- a/Documentation/trace/postprocess/trace-vmscan-postprocess.pl
+++ b/Documentation/trace/postprocess/trace-vmscan-postprocess.pl
@@ -123,7 +123,7 @@ my $regex_writepage;
# Static regex used. Specified like this for readability and for use with /o
# (process_pid) (cpus ) ( time ) (tpoint ) (details)
-my $regex_traceevent = '\s*([a-zA-Z0-9-]*)\s*(\[[0-9]*\])\s*([0-9.]*):\s*([a-zA-Z_]*):\s*(.*)';
+my $regex_traceevent = '\s*([a-zA-Z0-9-]*)\s*(\[[0-9]*\])(\s*[dX.][Nnp.][Hhs.][0-9a-fA-F.]*|)\s*([0-9.]*):\s*([a-zA-Z_]*):\s*(.*)';
my $regex_statname = '[-0-9]*\s\((.*)\).*';
my $regex_statppid = '[-0-9]*\s\(.*\)\s[A-Za-z]\s([0-9]*).*';
@@ -270,8 +270,8 @@ EVENT_PROCESS:
while ($traceevent = <STDIN>) {
if ($traceevent =~ /$regex_traceevent/o) {
$process_pid = $1;
- $timestamp = $3;
- $tracepoint = $4;
+ $timestamp = $4;
+ $tracepoint = $5;
$process_pid =~ /(.*)-([0-9]*)$/;
my $process = $1;
@@ -299,7 +299,7 @@ EVENT_PROCESS:
$perprocesspid{$process_pid}->{MM_VMSCAN_DIRECT_RECLAIM_BEGIN}++;
$perprocesspid{$process_pid}->{STATE_DIRECT_BEGIN} = $timestamp;
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_direct_begin/o) {
print "WARNING: Failed to parse mm_vmscan_direct_reclaim_begin as expected\n";
print " $details\n";
@@ -322,7 +322,7 @@ EVENT_PROCESS:
$perprocesspid{$process_pid}->{HIGH_DIRECT_RECLAIM_LATENCY}[$index] = "$order-$latency";
}
} elsif ($tracepoint eq "mm_vmscan_kswapd_wake") {
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_kswapd_wake/o) {
print "WARNING: Failed to parse mm_vmscan_kswapd_wake as expected\n";
print " $details\n";
@@ -356,7 +356,7 @@ EVENT_PROCESS:
} elsif ($tracepoint eq "mm_vmscan_wakeup_kswapd") {
$perprocesspid{$process_pid}->{MM_VMSCAN_WAKEUP_KSWAPD}++;
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_wakeup_kswapd/o) {
print "WARNING: Failed to parse mm_vmscan_wakeup_kswapd as expected\n";
print " $details\n";
@@ -366,7 +366,7 @@ EVENT_PROCESS:
my $order = $3;
$perprocesspid{$process_pid}->{MM_VMSCAN_WAKEUP_KSWAPD_PERORDER}[$order]++;
} elsif ($tracepoint eq "mm_vmscan_lru_isolate") {
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_lru_isolate/o) {
print "WARNING: Failed to parse mm_vmscan_lru_isolate as expected\n";
print " $details\n";
@@ -387,7 +387,7 @@ EVENT_PROCESS:
}
$perprocesspid{$process_pid}->{HIGH_NR_CONTIG_DIRTY} += $nr_contig_dirty;
} elsif ($tracepoint eq "mm_vmscan_lru_shrink_inactive") {
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_lru_shrink_inactive/o) {
print "WARNING: Failed to parse mm_vmscan_lru_shrink_inactive as expected\n";
print " $details\n";
@@ -397,7 +397,7 @@ EVENT_PROCESS:
my $nr_reclaimed = $4;
$perprocesspid{$process_pid}->{HIGH_NR_RECLAIMED} += $nr_reclaimed;
} elsif ($tracepoint eq "mm_vmscan_writepage") {
- $details = $5;
+ $details = $6;
if ($details !~ /$regex_writepage/o) {
print "WARNING: Failed to parse mm_vmscan_writepage as expected\n";
print " $details\n";
diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
index d9c3e682312c..f1cf9a34ad9d 100644
--- a/Documentation/trace/uprobetracer.txt
+++ b/Documentation/trace/uprobetracer.txt
@@ -19,18 +19,44 @@ user to calculate the offset of the probepoint in the object.
Synopsis of uprobe_tracer
-------------------------
- p[:[GRP/]EVENT] PATH:SYMBOL[+offs] [FETCHARGS] : Set a uprobe
- r[:[GRP/]EVENT] PATH:SYMBOL[+offs] [FETCHARGS] : Set a return uprobe (uretprobe)
- -:[GRP/]EVENT : Clear uprobe or uretprobe event
+ p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a uprobe
+ r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
+ -:[GRP/]EVENT : Clear uprobe or uretprobe event
GRP : Group name. If omitted, "uprobes" is the default value.
EVENT : Event name. If omitted, the event name is generated based
- on SYMBOL+offs.
+ on PATH+OFFSET.
PATH : Path to an executable or a library.
- SYMBOL[+offs] : Symbol+offset where the probe is inserted.
+ OFFSET : Offset where the probe is inserted.
FETCHARGS : Arguments. Each probe can have up to 128 args.
%REG : Fetch register REG
+ @ADDR : Fetch memory at ADDR (ADDR should be in userspace)
+ @+OFFSET : Fetch memory at OFFSET (OFFSET from same file as PATH)
+ $stackN : Fetch Nth entry of stack (N >= 0)
+ $stack : Fetch stack address.
+ $retval : Fetch return value.(*)
+ +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
+ NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
+ FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
+ (u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield
+ are supported.
+
+ (*) only for return probe.
+ (**) this is useful for fetching a field of data structures.
+
+Types
+-----
+Several types are supported for fetch-args. Uprobe tracer will access memory
+by given type. Prefix 's' and 'u' means those types are signed and unsigned
+respectively. Traced arguments are shown in decimal (signed) or hex (unsigned).
+String type is a special type, which fetches a "null-terminated" string from
+user space.
+Bitfield is another special type, which takes 3 parameters, bit-width, bit-
+offset, and container-size (usually 32). The syntax is;
+
+ b<bit-width>@<bit-offset>/<container-size>
+
Event Profiling
---------------
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-28 06:15:38 +0000